Thermal texturing of rock



Feb. 19, 1957 rrc so ET AL 2,781,754

THERMAL TEXTURING OF ROCK CIRCULAIEISG OVERFLOW 1 J WA I I U1 2? 10 20 22 U COURSE STONE MULTIFLAME GRA'N MULTIFLAME SLAB HEATING HEAD SURFACE HEATING HEAD Z0- TEXTURED SURFACE TEXTURED SURFACE lNl/EN TORS 1 ROBERT B. AITCHTSON DAVID H.FLEMING, JR. HARRY VJNSKEEP ATTORNE RAYMOND E. ARM STRONG, JR.

shot.

United States Patent THERMAL TEXTUR'ING OF ROCK Robert B. Aitchison, New York, N. Y., and David H.

Fleming, Jr., Chatham, and Harry V. Inskeep, Plainfield, N. J., and .Raymond E. Armstrong, Jr., Clark Township, N. Y., assignorsto Union Carbide and Carhon Corporation, a corporation of New York' Application December 19, 1955, Serial No, 553,867

Claims. (Cl, 125-1) The present invention relates to the thermal texturing of. rock and, more particularly, to the thermal texturing of course-grained rock surfaces under the influenceof a high temperature flame.

In the quarrying art, huge blocks of granite are taken from the quarry and are then cut into smaller blocks by sawing for use in monuments and for industrial purposes. Saws produce rough, scored surfaces having numerous hills and valleys which may be %;-inch or more in height or depth. Such rough surfaces have in the past been smoothed off by impacting tools, such as pneumatic I 2,781,754 I l aten ted Feb. 19, ms?

appreciable effect in material removal. By maintaining I a slight acute angle between the surface of the stone slab and the flame, in the direction of movement of the'flame,

the particles spalled off by the flame are blown away from I the direction of movement and do not interfere with the spalling action of the flame.

i and blowpipe;

hammers, and when a very smooth surface is required grinding has been used. 'These mechanical smoothing procedures are slow and expensive to perform, and impacted surfacing leaves the treated surface with bruises and minute cracks and requires a large investment in heavy and expensive machinery. Bruises and cracks in the surface are undesirable because water may be absorbed subsequently and upon freezing will cause the surface material to disintegrate. Also such a surface tends to absorb and retain dirt, which detracts from its physical appearance.

Another method for texturing the surface of such rock bodies is disclosed in U. S. Patent No. 2,655,909 to R. B. Aitchison et al. and involves passing a series of high temperature flames across the surface of a slab of the rock body to remove material therefrom by thermal spalling phenomena and produce a textured surface. While such method was successful in producing textured surfaces on dimension stone slabs, the application of such large quantities of heat can produce deleterious internal stresses which will result in cracking of the slab. In addition, due to the high rate of heat input to the stone slab, only relatively thick slabs could be processed. Thin slabs were very easily cracked by the high internal stresses generated by the high temperature attained, through the use of the high temperature flamejets.

It is, therefore,-the prime object of the present invention toprovide a novelmethod for thermally'texturing V the surface of a rough sawed stone slab without the danger of cracking the slab.

Another object of the invention is to provide such a method wherein the surfaces of thin stone slabs can be textured without cracking.

Other aims and advantages of the invention will be apparent from the following description and appended claims.

In accordance with the present invention there is provided a novel method for thermal texturing rough sur-' faces of sawed spallable stone slabs, having numerous ridges thereon, which comprises immersing the slab'in a body of water to a depth where a substantially uniform protective water film of at least -inch depth is pro vided above the surface of the slab, and passing a wide ribbon-like flame across the surface of the slab to remove portions of the surface including the ridges. The flame may be directed either normal to the surface of the stone slab or at an acute angle thereto without any In the drawing:

Fig. 1 is a vertical sectional view of apparatus suitable for performing the thermal texturing-method of the invention, showing the water tank, immersed stone slab Fig. 2 is a partial sectional'view-of a stone slab' treated' in accordance with the method of the invention, showing the surface before and after treatment by the flame ac tion;

.Fig. 3 is a partial plan view of the stone slab, showing the surface before and after treatment by the flame action; and 1 Fig. 4 is. a perspective view showing thermal texturing in accordance with the invention of portions of a stone slab of area determined by a pattern.

Referring specifically to Figs. 1 through 3 of the drawing, a tank 10 is provided having inlet means 12 and outlet means 14 for the circulation of water or other suitable coolant liquid ithereth r'ough. In accordance with the positioning'of overflow outlet conduit'means 14, a

heightlfiof ci'rculating liquid 18 is maintained in tank 10. A dimension 'stone slab 20 of spallable material, such as granite or the like, is immersed in the circulating liquid and supported by means of supports 22 so that a thin film 24 of water covers the surface 26 of the stone slab 20. A track 30 and carriage 32 assembly is provided for supporting blowpipe 34 above the surface'of the slab, and elevating means 36 are provided for adjusting the positioning of the blowpipe 34 with respect to the surface 26 of the slab 20.

Fig. 4 shows an oxy-fuel gas blowpipe 34 having a wide nozzle 40 adapted to produce a series ofsmall parallel oxy-fuel gas flame jets 42 arranged-close together and merging laterally to form, in effect, a ribbon or sheet of flame 44 across the path to be traversed. Suitable blowpipes for this purpose are shown in U. S. Patents Nos. 2,337,084 and 2,356,196, and these blowpipes may be operated either mechanically or manually to perform the method of the present invention.

The tip 46 of nozzle 40 is maintained at a substantially constant distance from the surface of the stone slab to effect a substantially uniform removal of surface material. The high temperature flame imparts heat to the course sawed surface and ridges flake or spall off under the effect of the heat. The thin film of water maintained above the surface of the stone slab is preferably maintained circulating and of the order of As-inch to 4 -inch in depth.- As the wide ribbon flame is traversed across the stone slab to thermally texture the surface, the high temperature flame jets momentarily force back the thin film of water covering the surface, and immediately thereafter the water flows back over the surface to keep the stone free from local temperature build-up which causes internal heat stresses.

\Nhile thin stone slabs were not heretofore capable of thermal texturing due to the rapid "build-up of internal heat stresses, very thin granite slabs have been thermally textured in accordance with the invention and used as veneer. 2 /2 inches thick. By sawing such a slab into twopieces and then erasing, by the method of the present invention, the rough, dull appearance left by the sawing action, there will be produced two thin veneer slabs having twice the surface and one-half the weight of prior products.

It is sometimes desirable to finish the surface of a stone slab only at predetermined locations. I This maybe accom Ordinarily, granite veneeiyfor example, is about.

plished by the method of the present invention by employing a pattern 48, such as shown in Fig. 4 of the drawing, wherein flame texturing is effected only on the stone surface exposed through the pattern. Since the thermal texturing is limited to small areas exposed through the pattern, such areas are subjected to intense local heating which would cause cracking of the slab, were it not for the fact that the slab is immersed in a body of water.

It has been found that any high temperature ribbonlike flames may be employed in the method of the present invention, and thermal texturing may be accomplished at various speeds depending upon the surface texture desired and the depth of the thin water film. Speeds of 12 to 70 inches per minutes have been employed successfully to thermal texture granite slabs in accordance with the method of the invention when employing protective water films of the order of /s-'inch to 4-inch in depth above the sur face of the slab. In suc'h'operations, a wide ribbon oxyacetylene flame was employed and dimension stone slabs as thin as %-inch were so treated.

While the principles in the invention have been described in detail in connection with the thermal text-uring of granite, it is to be understood that they equally apply to the thermal texturing of other spallable rock slabs, such as quartzite, sandstone, dolomite and the like.

What is claimed is:

1. In the method of thermal texturing the surface of a body of spallable rock by the application of a wide ribbonlike oxy-fuel flame in a direction transversely of said flame across the surface of said body of spallable rock, the improvement which comprises carrying out said thermal texturing while said body of rock is immersed in a liquid coolant so that a thin substantially uniform protective layer of such coolant is provided above the surface of said body.

2. The method in accordance with claim 1, wherein said coolant is water.

3. In the method of thermal texturing of the surface of a body of spallable rock by the application of a wide ribbon-like oxy-fuel flame in a direction transversely of said flameacross the surface of said body of spallable rock, the improvement which comprises carrying out said thermal texturing while said body of rock is immersed in a liquid coolant so that a thinsubstantially uniform protective layer of such coolant at least A -inch in depth is provided above the surface of said body.

4. The method in accordance with claim 3, wherein said coolant is water.

5. .A method for thermal texturing the surface of a body of spallable rock comprising, immersing said body in a liquid coolant so that a thin substantially uniform protective layer of such coolant is provided above the surface of said body, traversing a wide ribbon-like oAy-fuel flame transversely of said flame along the surface of said body to remove portions of said surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,278,214 Rausch Sept. 10, 1918 2,655,909 Aitchison et a1. Oct. 20, 1953 V FOREIGN PATENTS 21,846 Australia Aug. 15, 1929 

